(1) Field of the Invention
This invention concerns a cylinder driving apparatus for driving a load upwardly and downwardly.
(2) Description of the Prior Art
In conventional cylinder apparatus of general tgpe employed so far, in order to drive heavy load, double acting cylinders of large diameter capable of generating driving force greater than the weight of the load have been used. This, however, requires an extremely large amount of air to be charged and discharged into and from the cylinder for driving the load. Further, since no fine control is possible for the amount of air charged and discharged in the use of the large diameter cylinder, various defects have resulted. For instance, it provides an imbalanced property, that is, slow starting for the upward stroke and rapid starting for the downward stroke in the control for the driving of the load, smooth deceleration is difficult midway in the stroke and is accompanied by vibrating bounding actions, violent collision occurs at the stroke end and emergency stop can be attained only after the damping of vibrations.